Releasing hand-reared orphan sloths back into the wild

Can an orphan sloth that has been hand-reared in a rescue center survive after being released into the rainforest? As humans, can we raise that baby in a way that equips it with the survival skills necessary to safely navigate the treetops, find its own food and avoid predators? And what about the sloths internal immune-system defences: will these be strong enough after being raised in a sterile environment? There is only one way to find out, and so we are collaborating with the Jaguar Rescue Center to do exactly that!

The rehabilitation and release of orphan sloths is of increasing importance in the conservation and management of the species. In recent years there has been a rapid increase in the number of sloths arriving at wildlife rescue facilities in Central and South America, and although the species is not globally threatened, they are now recognised to be of conservation concern in Costa Rica. Sloths are requiring frequent rescue due to the loss or fragmentation of their habitat, disease, injury (often associated with traffic collisions, electrocutions or dog attacks), death of a mother with dependent young, or the necessity to relocate a sloth away from a dangerous location.

The primaryIMG_0600 aim of wildlife rehabilitation should always be to return each individual to the wild with maximum chances of survival whenever possible. A release is generally considered to be a success if the animal integrates into the wild breeding population and reproduces. The factors contributing to survival post-release are more complex for those sloths that have been orphaned and raised in captivity by humans compared to relocated or rehabilitated adults. A baby sloth is thought to stay with the mother for a full 12 months, during which time it acquires the essential skills required to survive in the wild. While many aspects of the sloth’s behaviour may be innate, certain skills must be learned. One such skill is knowing which leaves are safe to eat and where to find them, and this is a crucial lesson that wildlife rehabilitators must overcome to ensure an orphan sloth survives post-release.

To date no published studies have been carried out to determine the fate of rehabilitated, captive-reared or relocated sloths after release. Although sloths have been hand-reared and released into the wild by numerous organisations for over a decade, there has been no clear understanding of their fates because post-release monitoring with radio-telemetry has not been a common practice. This is due in part to the logistical problems associated with monitoring a cryptic arboreal species in a dense tropical rainforest, and also due to the financial burden of purchasing radio-telemetry equipment for rescue centres who receive no government funding. Consequently, there is much debate over whether hand-reared sloths can survive in the wild at all, with some institutions choosing to maintain orphan sloths as permanently captive animals to ensure their safety. With the increase in sloths arriving at rescue centres and the rapidly growing conservation concern for the species, it is becoming imperative that a standard protocol is established which enables organisations to achieve the optimum welfare outcome for each individual, whatever that may be! For sloths that do not have any physical impairments, disease or genetic problems, the ultimate goal of all wildlife rescue facilities needs to be to return these individuals back to the wild with long-term post release monitoring.

tracking

Post-release monitoring can be grouped into 3 broad data categories: survival, movement and behavioural data. While most release efforts that utilise radio-telemetry typically only monitor the length of time an animal can be located in the wild, this can often leave it difficult to determine whether an animal’s death was due to natural causes, or because the animal was not properly prepared for release. To effectively evaluate the success of a release protocol it is therefore important to combine data on the animal’s movement patterns and post-release behaviour with any changes in the overall physical condition of the animal and comparisons with similar data from wild populations.

Back to the Wild

Here at SloCo we are incredibly excited be launching a long-term collaborative study to monitor and document the survival of radio-collared hand-reared sloths after being released from the Jaguar Rescue Center (JRC) in Costa Rica.

scales

The first 4 sloths scheduled for release were all rescued as tiny orphans (all weighing less than 600 grams) over 2 years ago and have now been equipped with VHF tracking collars and moved into the JRC’s state-of-the-art soft release enclosure.  This jungle enclosure is built over 30 meters in the air and is ideal for getting the sloths used to being up high in the rainforest canopy. The doors are scheduled to open in May 2019, and we will be tracking and reporting on the progress of these sloths for the next 2 years!